14,049 research outputs found

    Relationships and events: towards a general theory of reification and truthmaking.

    Get PDF
    We propose a novel ontological analysis of relations and relationships based on a re-visitation of a classic problem in the practice of knowledge repre- sentation and conceptual modeling, namely relationship reification. Our idea is that a relation holds in virtue of a relationship's existence. Relationships are therefore truthmakers of relations. In this paper we present a general theory or reification and truthmaking, and discuss the interplay between events and rela- tionships, suggesting that relationships are the focus of events, which emerge from the context (the scene) they occur in

    Surface forces in particle technology: Wet systems

    Get PDF
    Surface forces play a fundamental role in particle processing as they control the stability, adhesion, friction and rheology of particulate systems and information on all of these can be obtained from an analysis of the normal forces measured between particles. Therefore particle processing at all stages can be informed by knowledge of the forces between the constituent particles. For wet particles systems, the interaction forces between two particles can rarely be predicted from theory, but rather requires experimentation or direct measurement. This requires that the surfaces used have the same as surface properties as the particles. In practice this is rarely possible, as surface force measurements require surfaces with extremely low roughness and precise geometry and the majority of materials do not conform to these requirements. To address these challenges we produce surfaces of low roughness and controlled chemistry using Atomic Layer Deposition (ALD) and are developing methods to calculate and understand the influence of surface roughness on the measured forces. Here we report the forces between hafnia surfaces produced by ALD and show that like ALD produced titania surfaces and silica surfaces, the expected van der Waals forces at high pH are not manifest, suggesting that most real surfaces have unexpectedly repulsive surface forces at high pH and small separations. This will fundamentally alter how these particulate systems behave when being processed, reducing the adhesion and the friction and enhancing the stability compared to the expected interaction from DLVO theory

    Rewiring strategies for changing environments

    Get PDF
    A typical pervasive application executes in a changing environment: people, computing resources, software services and network connections come and go continuously. A robust pervasive application needs adapt to this changing context as long as there is an appropriate rewiring strategy that guarantees correct behavior. We combine the MERODE modeling methodology with the ReWiRe framework for creating interactive pervasive applications that can cope with changing environments. The core of our approach is a consistent environment model, which is essential to create (re)configurable context-aware pervasive applications. We aggregate different ontologies that provide the required semantics to describe almost any target environment. We present a case study that shows a interactive pervasive application for media access that incorporates parental control on media content and can migrate between devices. The application builds upon models of the run-time environment represented as system states for dedicated rewiring strategies

    Demonstration of multi-channel 80 Gbit/s integrated transmitter and receiver for wavelength-division multiplexing passive optical network and fronthauling applications

    Get PDF
    The performance evaluation of a multi-channel transmitter that employs an arrayed reflective electroabsorption modulator-based photonic integrated circuit and a low-power driver array in conjunction with a multi-channel receiver incorporating a pin photodiode array and integrated arrayed waveguide grating is reported. Due to their small footprint, low power consumption and potential low cost, these devices are attractive solutions for future mobile fronthaul and next generation optical access networks. A BER performance of <10(-9) at 10.3 Gbit/s per channel is achieved over 25 km of standard single mode fibre. The transmitter/receiver combination can achieve an aggregate bit rate of 82.4 Gbit/s when eight channels are active

    High Mass Triple Systems: The Classical Cepheid Y Car

    Full text link
    We have obtained an HST STIS ultraviolet high dispersion Echelle mode spectrum the binary companion of the double mode classical Cepheid Y Car. The velocity measured for the hot companion from this spectrum is very different from reasonable predictions for binary motion, implying that the companion is itself a short period binary. The measured velocity changed by 7 km/ s during the 4 days between two segments of the observation confirming this interpretation. We summarize "binary" Cepheids which are in fact members of triple system and find at least 44% are triples. The summary of information on Cepheids with orbits makes it likely that the fraction is under-estimated.Comment: accepted by A

    Analysis of Dialogical Argumentation via Finite State Machines

    Get PDF
    Dialogical argumentation is an important cognitive activity by which agents exchange arguments and counterarguments as part of some process such as discussion, debate, persuasion and negotiation. Whilst numerous formal systems have been proposed, there is a lack of frameworks for implementing and evaluating these proposals. First-order executable logic has been proposed as a general framework for specifying and analysing dialogical argumentation. In this paper, we investigate how we can implement systems for dialogical argumentation using propositional executable logic. Our approach is to present and evaluate an algorithm that generates a finite state machine that reflects a propositional executable logic specification for a dialogical argumentation together with an initial state. We also consider how the finite state machines can be analysed, with the minimax strategy being used as an illustration of the kinds of empirical analysis that can be undertaken.Comment: 10 page

    From Oxford to Bristol and Back: The Invention of Scientific Wildlife Television

    Get PDF
    In the 1960s, two scientists from Oxford University, Niko Tinbergen and Gerald Thompson, began using film as part of their scientific practice. The BBC’s Natural History Unit (NHU) in Bristol quickly got wind of their work and started collaborating with them to develop a new approach to wildlife television making. Tinbergen, the founder of ethology, brought intellectual foundations to it, creating, with Christopher Parsons, stories of wildlife informed by the theory of evolution. Thompson provided a technological edge which enabled the Bristol NHU producers to bring a new perspective to the subject matter they were showing in their programmes. The two collaborations also led them to further define their identity as experts in wildlife television making

    Electron-hole imbalance in superconductor-normal metal mesoscopic structures

    Full text link
    We analysed the electron-hole or, in another words, branch imbalance (BI) and the related electric potential VimbV_{imb} which may arise in a mesoscopic superconductor/normal metal (S/N) structure under non-equilibrium conditions in the presence of a supercurrent. Non-equilibrium conditions can be created in different ways: a) a quasiparticle current flowing between the N reservoirs; b) a temperature gradient between the N reservoirs and no quasiparticle current. It is shown that the voltage VimbV_{imb} oscillates with the phase difference ϕ\phi. In a cross-geometry structure the voltage VimbV_{imb} arises in the vertical branch and affects the conditions for a transition into the π\pi-state.Comment: 6 pages, 5 figures, accepted for publication in Europhysics Letter

    The First Swift BAT Gamma-Ray Burst Catalog

    Get PDF
    We present the first Swift Burst Alert Telescope (BAT) catalog of gamma-ray bursts (GRBs), which contains bursts detected by the BAT between 2004 December 19 and 2007 June 16. This catalog (hereafter BAT1 catalog) contains burst trigger time, location, 90% error radius, duration, fluence, peak flux, and time averaged spectral parameters for each of 237 GRBs, as measured by the BAT. The BAT-determined position reported here is within 1.75' of the Swift X-ray Telescope (XRT)-determined position for 90% of these GRBs. The BAT T_90 and T_50 durations peak at 80 and 20 seconds, respectively. From the fluence-fluence correlation, we conclude that about 60% of the observed peak energies, Epeak, of BAT GRBs could be less than 100 keV. We confirm that GRB fluence to hardness and GRB peak flux to hardness are correlated for BAT bursts in analogous ways to previous missions' results. The correlation between the photon index in a simple power-law model and Epeak is also confirmed. We also report the current status for the on-orbit BAT calibrations based on observations of the Crab Nebula.Comment: 63 pages, 23 figures, Accepted in ApJS, Corrected for the BAT ground position, the image significance, and the error radius of GRB 051105, Five machine-readable tables are available at http://swift.gsfc.nasa.gov/docs/swift/results/bat1_catalog

    Confirmation of the \eps -- \eiso (Amati) relation from the X-ray flash XRF 050416A observed by Swift/BAT

    Full text link
    We report Swift Burst Alert Telescope (BAT) observations of the X-ray Flash (XRF) XRF 050416A. The fluence ratio between the 15-25 keV and 25-50 keV energy bands of this event is 1.5, thus making it the softest gamma-ray burst (GRB) observed by BAT so far. The spectrum is well fitted by the Band function with E^{\rm obs}_{\rm peak} of 15.0_{-2.7}^{+2.3} keV. Assuming the redshift of the host galaxy (z = 0.6535), the isotropic-equivalent radiated energy E_{\rm iso} and the peak energy at the GRB rest frame (E^{\rm src}_{\rm peak}) of XRF 050416A are not only consistent with the correlation found by Amati et al. and extended to XRFs by Sakamoto et al., but also fill-in the gap of this relation around the 30 - 80 keV range of E^{\rm src}_{\rm peak}. This result tightens the validity of the E^{\rm src}_{\rm peak} - E_{\rm iso} relation from XRFs to GRBs. We also find that the jet break time estimated using the empirical relation between E^{\rm src}_{\rm peak} and the collimation corrected energy E_{\gamma} is inconsistent with the afterglow observation by Swift X-ray Telescope. This could be due to the extra external shock emission overlaid around the jet break time or to the non existence of a jet break feature for XRF, which might be a further challenging for GRB jet emission, models and XRF/GRB unification scenarios.Comment: 16 pages, 4 figures; accepted for publication in ApJ
    • …
    corecore